See the [nucleus] before the message? That means that the plugin nucleus is the one logging it to the console. You probably need to either tell nucleus not to do it (via a config), or remove nucleus, or maybe a patch can be pushed out via FlexibleLogin.

# +------------------------------------------------------------+
# | Command Logger |
# +------------------------------------------------------------+
command-logger {
# A comma separated list of commands in the blacklist or whitelist (see whitelist option). Only one alias per command is required.
command-filter=[
login,
register
]
# If any option is true, log commands from the source.
log-command-source {
command-block=false
console=true
other-source=true
subject=true
}
# If true, will log commands to files at /logs/nucleus/commands
log-to-file=true
# If true, the "command-filter" containing the list of commands to be logged is a whitelist (command must be specfied to be logged), not a blacklist.
whitelist=false
}

Please fix
the command
/unregister <uuid|name> - delete an account
doesn’t work at all
the mail settings doesnt work at all so basically if you forget your password you will not be able to play on the server again

I cannot fix things if you don’t describe the bug you are having. I often wrote that to others too. Always describe the situation. “doesn’t work” doesn’t help me to fix it. Take a look at the server log, are there any errors? What have you tried and what was the expected and actual outcome? Which version do you run? The password recovery bug sounds familiar and got already fixed in a dev-build. Do you tried that? Do you searched through the bug tracker for that same bug?

Plugin is outdated?
I have problem with database file creation, i use local database, and with default config i have crash with reason “HikariPool-2 - Cannot acquire connection from data source
org.h2.jdbc.JdbcSQLException: Error while creating file”
I use spongeforge-1.12.2-2768-7.1.6-RC3666